Washington Mills has developed a process that enables it to collect spent aluminum oxide and recycle it back into the manufacturing process.
Blasting grain produced by crushing chunks of fused alumina.
Over 150,000 tons of fused
aluminum oxide is consumed annually in the U.S., and only a very small portion
of that tonnage is recycled. Prices for the raw materials used in manufacturing
fused aluminum oxide have spiked to historically high levels. For example,
bauxite has become increasingly more difficult to source, and prices have more
than doubled in the past year alone. China, a major supplier of bauxite, has
experienced a mix of pivotal events that have directly contributed to upward
pressure on bauxite prices: soaring Chinese power costs, increased Chinese
domestic demand for bauxite in the aluminum industry, stricter environmental
controls on calcined bauxite, plant closures, and increased transportation
costs. This paradigm shift in the global commodities market has strengthened
the economic case for the recycling of aluminum oxide.
Traditionally, spent aluminum oxide is brought to a landfill for final
disposal, but rising landfill costs, tighter landfill regulations and higher
freight costs are causing businesses to rethink their waste disposal practices.
As one the largest manufacturers of aluminum oxide in the U.S., Washington
Mills is aware of the growing need to find better ways to dispose of spent
abrasive grain. In an effort to address this need, Washington Mills has worked
with large-volume users of its BLASTITE®
blasting grain to collect the spent aluminum oxide and recycle it back into the
Washington Mills has invested significant
research and development resources to make its aluminum oxide manufacturing
process a completely closed-loop manufacturing system. When other industry
players closed down their aluminum oxide furnaces and opted to produce or
source from China, Washington Mills made the strategic decision to continue
manufacturing fused aluminum oxide in North America. Today, as the only
manufacturer of fused aluminum oxide in North America operating its own furnace
plants, Washington Mills is able to reintroduce the spent aluminum oxide back
into its furnace operation.
In Washington Mills’ recycling program, the spent aluminum oxide grit is reused
as an ingredient for making new fused aluminum oxide. The spent aluminum oxide
is blended with new bauxite, and this mixture is fed into specially designed
furnaces that melt and purify the liquid abrasive. The company’s furnace
expertise enables it to transform the spent aluminum oxide back into raw
materials used to make pure fused aluminum oxide. Recycling used aluminum oxide
by putting it back into the furnace that it originally came from and using it
to make new fused aluminum oxide is a 100% closed-loop manufacturing system.
The perpetual recycling loop produces no waste and reduces dependency on new
raw materials. Washington Mills successfully makes pure fused aluminum oxide
from recycled material that has the same chemistry and crystal structure as
fused aluminum oxide made from new raw materials.
An electrode supplies power (center) while raw materials are added to a furnace via feed chute (right).
Washington Mills has worked over the years to
modify its furnace operations to accommodate the use of spent aluminum oxide.
Furnacing aluminum oxide is not a simple process. It requires charging the
furnace with a raw material mix that has the correct chemistry and stability
for the materials to effectively and safely fuse together. When introducing
non-virgin raw materials, such as spent aluminum oxide, the chemistry of the
raw material mix is constantly changing. The furnace process just can’t reduce
certain chemistries, so it is important to be diligent about testing the
recycled materials and mixing together the right ratio of materials to achieve
the desired chemistry.
Washington Mills has a strict testing program for all spent aluminum
oxide before the grit can be accepted for recycling. The company tests the
chemistry of the material until it is certain that the spent material will work
in the furnace process. Depending on the surface that was being blasted, the
spent abrasive grain may contain different metals or other elements that were
picked up in the blasting process. In many applications, the small amount of
debris in the spent grain does not pose a problem, but in others where perhaps
lead, cadmium or other elements were taken off in the blasting process, the
material would not be used for recycling.
Since the recipe changes with each new
recycling shipment, a sophisticated technical process was developed to enable
the company to handle the various chemical compositions and particle sizes of
the spent material. Washington Mills continually improves how it manages the
materials and adapts the raw material mix to suit the furnace process. The
company believes that innovation through the adaptation of the process to work
with alternative sources of raw materials gives it a manufacturing edge.
raw materials, the spent material is often returned in much finer particle
sizes. The material handling capabilities needed to manage materials of very
fine particle sizes, as well as myriad packing types, is a sizable challenge.
Finer materials are more difficult to handle and must often be agglomerated
before being fed into the furnace. Very fine material does not move well or
release easily into the furnace, so a considerable amount of work must be done
to prepare the material before use. In addition, the material is returned in
many different types of packages, from sacks to drums to bulk, which makes
operating an efficient material handling system a challenge.
A furnace operator takes a sample before pouring the liquid aluminum oxide.
Despite the challenges, the hard work devoted
to recycling programs pays real benefits in terms of offering a greater level
of service to customers, and in manufacturing a high-quality product in North
America at competitive prices. In today’s world of soaring raw material and
electricity costs, and the declining quality of raw material inputs, a
recycling program that reduces dependency on expensive raw materials to control
costs offers real value to fused aluminum oxide users.
Washington Mills believes it is helping its
customers break out of the one-way landfill trap of rising disposal costs by
continuing to refine its closed-loop recycling program. By bringing the spent
material back into the furnace and transforming it into fused aluminum oxide,
the company aims to maximize the customer experience while innovating itself
away from rising manufacturing costs.
For additional information regarding the
recycling of spent aluminum oxide, contact Anne Williams, Washington Mills,
1801 Buffalo Ave., Niagara Falls, NY 14302; (508) 839-6511, ext. 256; e-mail firstname.lastname@example.org; or visit www.washingtonmills.com.
SIDEBAR: Ready, Set, Blast
A primary consumer of fused aluminum oxide is
the metal preparation and finishing industry, which uses it as an abrasive
blasting media. In this application, the fused aluminum oxide grains, when
propelled by air pressure, become powerful multi-edged abrasive tools that
penetrate workpieces and leave clean, etched surfaces in their wake. The abrasive
particles remove contaminants and unwanted substances from the metal’s surface
to give it the desired finish. Blasting with fused aluminum oxide is a highly
effective method for either material removal or surface preparation on many
different surfaces, including metals, alloys, glass, ceramics, marble, granite,
and other stone.
Washington Mills’ BLASTITE BT blasting grain is an abrasive grain used in the
blasting industry. In pressure blasting, a pressurized stream of compressed air
is directed through a nozzle and onto a workpiece to create a uniform surface.
The blasting is done either in a blast cabinet or in a large blast room that
contains and collects the aluminum oxide after it has been blasted onto the
Depending on the piece being blasted or the desired surface profile, the
aluminum oxide may be collected and re-used for multiple passes through the
blasting system in order to maximize the abrasive life of the grain. Once the
abrasive particles have been reduced in size, the aluminum oxide is either
disposed of in a landfill or sent to Washington Mills for recycling.
SIDEBAR: Case in Point
One heavy manufacturing company was using
around 500 tons of fused aluminum oxide grit per year for a blasting
application. With a landfill cost of $60 a ton (costs differ depending on the
location), the company was spending $30,000 per year to put the spent aluminum
oxide into the ground. The company contacted Washington Mills to investigate
whether it could recycle the material. Washington Mills tested the spent grit
and determined it suitable for recycling.
The company developed a simple collection
system to gather the spent grit and started sending the material back to
Washington Mills for reuse in its recycling program. The manufacturer was able
to eliminate its landfill costs, and both parties reduced their impact on the
environment. Additionally, Washington Mills made a step toward reducing its raw
material costs, which, in the face of rising raw material prices, is a step
toward controlling costs for the benefit of both the manufacturer and the customer.